Rats and Mice

when an owner is bringing their pet in with the cage, what should you tell them?

DONT clean the cage! you want to see what the normal environment is for the animal

what time of day is best for appointments for rats?

evening- rats are nocturnal.

how difficult is it to collect a sample of urine/feces from a mouse or rat?

Rodents urinate and defecate when handled – be prepared to collect samples on your hands

how might bloodwork differ between a small rodent and a larger rodent?

Small: only PCV and smear. you can get a CBC and chem on a larger rodent, though

explain which gender is more agressive (and the exception is?)

agression is more common between males than females. The exception is female hamsters, of course

if you want to have mice or rats that all get along, what are the best two options?

either raise littermates together, or introduce at weaning

for any introduction, what do you wanna do with the environment?

Introduce animals in clean cage (neutral territory) (or do “soft introduction”), also make sure there are hiding places and observe closely for the first few days

when medicating mice/rats what must you be very mindful of?

get an ACCURATE WEIGHT and be CAREFUL with calculations. Use a compounding pharmacy or dilute medication appropriately. Can be mixed with food or water if palatable.

what kinda instrument can you use to medicate rats/mice?

TB or insulin syringes. If oral admin, can use a ball ended dosing needle

which injection routes are most preferred for mice/rats?

IV injections may be difficult, use intraperitoneal or subcutaneous routes instead

what should you think if you see a rat or mouse with orange teeth?

nothing-- it's normal

what is the growth of rat/mouse incisors like? molars?

the incisors are open rooted and grow continuously. the molars are fixed rooted

which incisors are longer in the rat/mouse, and what should you know about this?

Lower incisors are longer than upper – DO NOT CLIP

what is a diastema, and why do we like it?

the gap between the incisors and molars-- and it's great for getting medications in their mouth

what's a Harderian Gland? Where is it/what does it do?

this is a gland which is located behind the eye, and it Produces porphyrin and lipid rich secretions (lubrication, pheromones).

If you see "red tears" or red nasal discharge, what is happening?

This is the porphyrin and lipid rich secretions from the harderian gland, NOT BLOOD. The secretions can become excessive during stress or dz which is when you'd see them. You can make sure it's not blood because porphyrin will fluoresce under UV (Wood's lamp)

where are mammary tumors usually found?

can be found anywhere on the body in females OR males(the glands have wide distribution including the back)

If there is a SQ mass on a rat/mouse, it's probably?

mammary tumor until proven otherwise

how long should you fast a rat/mouse before anesthesia?

TRICK QUESTION! YOU DO NOT FAST before anesthesia

why do you not fast a mouse/rat before anesthesia?

two reasons: (1) they have a ridge between stomach and esophagus, so they do not vomit (2) they have a high metabolic rate

how do you sex rats/mice?

sex by the anogenital distance-- Male>Female. ((also male testicles can be manipulated into scrotum (open inguinal rings)- good for sexing also ).

PE stuff--> are there vx for rats/mice? what should you always check? what parameter should you always have?

no vx. Always check dentition (incisors grow continuously), and always get an accurate weight (always do full PE and make complete medical record)

how often should you change the water of rats/mice?

DAILY. they pee/poop in it

what kinda bedding is recommended?

coconut husk shavings, corncob, recycled paper, aspen bedding

anesthesia--> what's up with intubation in rats/mice?

impractical because they are so small. (There is a Technique using IV catheter silicone sleeve for trach tube in rats)...most of the time there is chamber induction followed by maintenance via face mask. (injectable anesthetics can be used)

(not sure how important) explain doing an ovariohysterectomy in rats/mice

*what is barbering? who does this and why does it happen? How can you tell that it's barbering? how do you tx it?

this happens with groups of housed mice. Dominant mouse nibbles whiskers and fur of subordinate cage mates. You can tell it's barbering because the skin of the affected mice appears normal, and only dominant mouse has all its fur. TX: enrichment or removal of dominant mouse

MICE--> two main causes of fight wounds?

incompatible males, introduction after weaning

what is the most common tumor in mice? what is tx/prognosis?

adenocarcinoma. You can sx excise, but there is a high recurrence rate and poor prognosis

*explain the size/relative location of the maxillary and mandibular incisors

(*remember incisors grow continuously) the mandibular incisors are longer than the maxillary, and the mandibular incisors are CAUDAL to the maxillary

(causes?) clinical signs of overgrown incisors? treatment?

(if opposing tooth is missing, or there is improper alignment or improper diet, this can happen.) you will usually see hypersalivation, anorexia and weight loss. TX: TRIM TEETH every 2-3mo.

thin, greasy haircoat, pruritus, SELF-INFLICTED TRAUMA (most of it isnt from the mites themslves). May be subclinical for weeks or months

are fur mites burrowing or non burrowing? how do you tx them?

they are non-burrowing so you can see the mites/nymphs/eggs with a magnifying glass. Tx with ivermectin (PO, SQ, topical) and trim hind toenails to prevent self mutilation

MICE---> Mouse Hepatitis Virus. What kinda virus is this? Age affected? what are the clinical signs? what's the tx?

this is a corona virus which affects neonates. you will see WASTING because of severe enteritis--> diarrhea, dehydration, jaundice. There will be no milk in the GI tract and the pups will be small. (also the liver looks all messed up) The only tx is supportive until the dz runs its course

Usually affects neonates. It's rota, so of course enteritis (milder than mouse hepatitis though), and you'll see diarrhea with soiling of hair coat. Tx is supportive, most of the time pups continue to nurse and usually survive

Sendai Virus--> affects who? what kinda body system does this virus manifest in? what's the DDX?

Rats AND mice, it's a resp. virus. DDX-mycoplasma

Sendai Virus--> what are the clinical signs? prognosis? tx?

CS: mild resp distress. Adults will recover in 2mo, FATAL in neonates and weanlings. TX is supportive, and to control ammonia levels (keep clean cage), and give abx (in case it is mycoplasma and not sendai)

Mycoplasma affects who? what kinda body system does it affect? How common is this dz?

Rats and mice, it is a resp. dz (Mycoplasma pulmonis). MOST PET MICE ARE CARRIERS and they will develop clinical dz when stressed or ill.

Advanced age >1yr. More severe in males. CS: PU/PD, proteinuria, Hydrothorax and ascites in advanced stages. TX is only supportive because this is a fatal dz, but calorie and protein restriction limits severity

Sialodacryoadenitis Virus--> who does this affect, what kinda virus is it, and what parts of the body are affected?

this is a viral dz of RATS, which is caused by a corona virus. *HIGHLY CONTAGEOUS*. Sialo= salivary gland. dacryo= tears. aden= gland. Itis=inflammation. Therefore, it's an inflammation of the salivary glands, cervical LNs, and Harderian gland

Sialodacryoadenitis Virus--> CSs and TX/prog?

CS: Red ocular and nasal discharge (hence the dacryo in the name). TX: no tx, it is a self-limiting infection of ~30 days, with high morbidity and low mortality.